Titanium cogs seem to wear out pretty fast (but nowhere near as fast as aluminum ones). Everyone thought this was going to be a “wondermaterial” for wear-prone components, but the truth of the matter is that it is not. Some company called Viking made a titanium drive chain back in the day ($200 or so in 1994 dollars), but it didn’t succeed.

I have a titanium wedding band and a titanium ring for my right hand, and they’re both scratched and gouged to hell. I take them off for most chores, too. The only one that has survived is a tungsten ring my wife bought me…sharp enough to cut glass and only a couple tiny scratches despite some brutal use.